Pressure regulating unit for supplying a pressurized fluid from alternative supply lines

ABSTRACT

A pressure regulating unit for supplying a pressurized fluid, especially breathing gas, to a user, which unit comprises a pressure regulator (3, 22-29) and a switching means (1, 9, 10, 13-20) for controlling the fluid supply from a preferential supply line (6) and an alternative supply line (8) to a common outlet (12) from the unit. The unit comprises a first chamber (13) which is in open connection (16) with the preferential supply line (6), and which contains a spring-actuated first sensing diaphragm (14) sensing the pressure in the preferential line (6) and being operatively connected to and driving the valve means (9, 10, 17-20). This is designed so that it keeps the preferential line (6) connected to an outlet chamber (11) and the alternative line (8) shut-off as long as the pressure in the preferential line (6) is sufficient to maintain a desired outlet pressure from the unit, but connects the alternative line (8) to the outlet chamber (11) and shuts off the preferential line (6) when the pressure therein drops below a certain value. Further, the unit includes a pressure regulator which sees that the pressure at the outlet (12) of the unit is kept stable on the desired outlet pressure.

The invention relates to a pressure regulating unit for supplying apressurized fluid, especially breathing gas, to a user, which unitcomprises a pressure regulator and a switching means for controlling thefluid supply from a preferential supply line and an alternative supplyline to a common outlet from the unit, the switching means including avalve means arranged to connect either of the two supply lines to theoutlet in dependence on the pressure in the supply lines.

Such a device is intended for use in situations wherein it is necessaryto maintain a stable outlet pressure from the unit even if the supplythrough the .preferential supply line disappears for shorter periods. Atopical example is in connection with the breathing gas supply to acombat plane pilot. In some situations, such as when starting and incombat situations, the pressure energy from the compressor of theairplane is used to drive the plane and the equipment thereof, so thatone does not have the necessary pressure for air supply to the pilot.The combat plane pilots therefore have an alternative breathing gassource, consisting of liquid pressurized oxygen, which is connected toan alternative supply line. This alternative source constitutes anemergency reservoir which--mainly because of space limitations--has arelatively small capacity. It is therefore essential that this emergencyreservoir is used as little as possible.

From U.S. Pat. No. 2,775,980 there is known a pressure regulating unitwherein a switching means controls gas supply from a pair of supplylines to a common outlet. The supply lines are connected throughrespective pressure regulators to separate high pressure sources ofwhich each consists of a battery of high pressure gas bottles. The unitis designed for automatically and without any discontinuity to ensurethe supply from the two supply lines to the common outlet in apredetermined order, the stand-by line being gradually connected andcompletely takes over the gas supply to the outlet only when thepressure in the supply line being drained has dropped below apredetermined critical value. The switching means comprises a valvehousing having a pair of interconnected spring-influenced diaphragmswhich cooperate with respective valve seats on opposite sides of thevalve housing, and which define respective chambers communicating with arespective high pressure source. Further, there is provided aspring-controlling means for influencing the springs so that one springapplies a greater thrust than the other, so that a greater thrust isapplied to the diaphragm assembly alternately in one direction and theother. Thereby one supply line may have priority over the other, so thatthe preferential line is maintained connected until the pressure dropsbelow the critical value. At that time this line is disconnected,whereas the other line then is completely connected and takes over thegas supply. Thereafter the spring-force controlling means is switchedover, so that the now connected second line takes priority while itshigh pressure source is drained until the pressure thereof has droppedto the critical value.

This device makes it possible to replace a drained gas bottle batterywith a fresh battery without the gas supply being disturbed, and withoutany switching of the pressure regulator of the unit being required.However, the device is intended for alternating draining of highpressure sources until the pressure of the utilized source has droppedto a certain value, and thus is not suitable for the application statedin the introduction.

Thus it is an object of the invention to provide a pressure regulatingunit having a switching means which at any time senses the pressure inthe preferential supply line, and which gives priority to supply throughthis line, so that the alternative supply line is used as little aspossible. Simultaneously, it is an object of the invention to providesuch a unit which sees that the pressure at the outlet of the unit ismaintained stable at a desired level.

The above-mentioned objects are achieved with a pressure regulating unitof the introductorily stated type which, according to the invention, ischaracterized in that it comprises a first chamber which is in openconnection with the preferential supply line, and which contains aspring-actuated first sensing diaphragm sensing the pressure in thepreferential line and being operatively connected to and driving thevalve means, so that it keeps the preferential line connected to anoutlet chamber and the alternative line shut-off as long as the pressurein the preferential line is sufficient to maintain a desired outletpressure from the unit, but connects the alternative line to the outletchamber and shuts off the preferential line when the pressure thereindrops below a certain value, and a second chamber which is in openconnection with the outlet of the unit, and which contains aspring-actuated second sensing diaphragm which is operatively connectedto a regulator element for control of the fluid flow from said outletchamber to the outlet of the unit, so that the pressure at the outlet iskept stable on the desired outlet pressure determined by the springforce on said diaphragm.

The invention will be further described below in connection with anexemplary embodiment with reference to the drawing, wherein

FIG. 1 shows a sectional view of a pressure regulating unit according tothe invention in a first operational condition; and

FIG. 2 shows a corresponding sectional view of the same unit in a secondoperational condition.

The device shown in the drawing constitutes an integrated pressureregulator and switching means, wherein the switching means essentiallycomprises a valve housing 1 (with an associated valve structure) and afirst diaphragm housing 2 in association therewith, and the regulatorcomprises a regulator element 3 in association with a second diaphragmhousing 4. As shown, the two diaphragm housings 2, 4 are disposed atopposite sides of the valve housing 1, this giving a compact and simpleconstruction of the unit in association with the remaining components.

The valve housing 1 has a first inlet 5 to which a first, preferentialsupply line 6 is connected, and a second inlet 7 to which a second,alternative supply line 8 is connected. The two inlets 5, 7 areconnected through respective valves 9, 10 (to be further describedlater) to a common valve or outlet chamber 11 which is connected throughthe regulator to a common outlet 12 from the unit.

The first diaphragm housing 2 defines a first chamber 13 in which afirst sensing diaphragm 14 is mounted in the shown manner, the diaphragmbeing clamped at its periphery and in its central area being actuated bya force-exerting means in the form of a spring 15 pressing the diaphragm14 with an adjustable force in the direction towards the chamber 13.Through a channel 16 (only suggested with dashed lines) the chamber 13is in open connection with the inlet 5 from the preferential supply line6, so that the diaphragm 14 at any time senses and is influenced by thepressure in this line.

As shown, the diaphragm 14 in its central area is connected to anoperating rod 17 which is displaceably arranged in the valve housing 1and on which there is mounted a first and a second valve body 18 and 19,respectively, forming part of a respective one of the two aforementionedvalves 9 and 10 controlling the connection between the respective supplylines 6, 8 and the common outlet chamber 11. The valve body 18 isdisplaceable on the operating rod 17 and is force-influenced in thedirection towards the associated valve seat by means of a spring 20, sothat the valve 9 is a one-way valve. The valve body 19 is fixedlymounted on the rod 17 at a suitable position for closing the valve 9when the valve 10 is opened with displacement of the rod when thepressure in the preferential supply line 6 drops below a certain value.

In the pressure regulator forming part of the unit, the regulatorelement 3 in the illustrated embodiment is in the form of aspring-loaded piston which is slidable in a cylinder guide 21 which isshown to be placed in a part of the valve housing 1. The piston 3 isoperatively connected to a second sensing diaphragm 22 which is mountedin the shown manner in a second chamber 23 which is defined by thesecond diaphragm housing 4 and through a passage 24 is in openconnection with the outlet 12 of the unit.

In a manner corresponding to that of the first sensing diaphragm 14 thesecond sensing diaphragm 22 is clamped at its periphery, and in itscentral area it is influenced by a spring 25 which, with an adjustableforce, actuates the diaphragm in the direction towards the chamber 23.The piston 3 is connected to the central area of the diaphragm 22through a connecting rod 26 extending through the passage 24, and alever 27.

Between the outlet chamber 11 of the valve means and the outlet 12 ofthe unit there is provided a flow passage 28 which is defined by one endof the piston 3 facing the diaphragm 22, and an annular seat 29. Thesize of this passage is controlled by the piston 3 in cooperation withthe sensing diaphragm 22. Since the chamber 23 is in open connectionwith the outlet 12, varying pressure at the outlet, and consequently inthe chamber 23, will result in that the piston controls the flow passage28 correspondingly, so that a stable outlet pressure is maintained, thespring force on the diaphragm 22 being adapted for this purpose.

The illustrated embodiment of the pressure regulator only represents anexample, since other embodiments may be of interest, such as will beclear to a person skilled in the art.

The operation of the unit broadly will be clear from the precedingdescription. In the situation in FIG. 1, the fluid supply takes placethrough the preferential supply line 6. The fluid flow passes theone-way valve 9 and through the outlet chamber 11 and the passage 28 tothe outlet 12, as shown by arrows. The position of the piston 3 relativeto the seat 29, and therewith the fluid flow to the outlet 12, iscontrolled by the spring-loaded diaphragm 22 the movement of whichactuates the piston through the lever 27 and the rod 26. Since thechamber 23 is in open connection with the outlet 12, the fluid flow pastthe piston is regulated automatically, so that the pressure ismaintained stable at the pressure required to balance the force from thespring 25.

FIG. 2 shows the situation with supply through the alternative supplyline 28. In this situation the pressure at the inlet 5, and consequentlyin the chamber 13, is too low to balance the force from the spring 15.The sensing diaphragm 14 and the operating rod 17 then are presseddownwards, and the valve body 19 opens the passage between thealternative line 8 and the chamber 11. The pressure in the chamber 11consequently becomes higher than at the inlet 5 of the preferentialline, and the one-way valve 9 is kept closed. When the pressure in thepreferential line again increases to the desired value, the sensingdiaphragm 14 is pressed upwards, so that the valve body 19 again closesthe passage between the alternative line 8 and the outlet chamber 11.The situation is then again as shown in FIG. 1.

I claim:
 1. A pressure regulating unit for supplying a pressurized fluid, such as breathing gas, to a user from one of a preferential supply line and an alternative supply line, said pressure regulating unit comprising:switching means for controlling fluid supply from one of the preferential supply line and the alternative supply line to a common outlet, said switching means comprising valve means connecting one of the preferential supply line and the alternative supply to said common outlet in dependence on a pressure in the preferential supply line, and a pressure regulator controlling fluid flow to said common outlet so as to maintain stable fluid pressure at said common outlet at a desired pressure level, said switching means further comprising a first chamber connected to the preferential supply line by a channel, and a spring-actuated first sensing diaphragm sensing the pressure in the preferential supply line and being operatively connected to and driving said valve means, said valve means comprising first and second valves connecting the preferential supply line to an outlet chamber, said first and second valves keeping the alternative supply line shut off as long as the pressure in the preferential line is above said desired pressure level and thus always giving priority to fluid flow through the preferential supply line, said first and second valves also connecting the alternative supply line to said outlet chamber and keeping the preferential supply line shut off when the pressure therein drops below said desired pressure level, said pressure regulator comprising a second chamber connected to said common outlet by a passage, said pressure regulator further comprising a spring-actuated second sensing diaphragm sensing fluid pressure at said common outlet and being operatively connected to a regulator element controlling the fluid flow from said outlet chamber to said common outlet so that the fluid pressure at the common outlet is maintained at said desired pressure level.
 2. The pressure regulating unit of claim 1 wherein an operative connection between said first sensing diaphragm and said first and second valves comprises a longitudinally displaceable operating rod attached to a central area of said first sensing diaphragm and on which there is mounted a valve body of each of said valves, the valve bodies controlling the connection between the preferential and alternative supply lines and said outlet chamber.
 3. The pressure regulating unit of claim 1 wherein said valve between said preferential supply line and said outlet chamber is a one-way valve.
 4. The pressure regulating unit of claim 1, wherein said valves and said regulator element are disposed in a common housing, and said first and second chambers are disposed at opposite sides of said housing.
 5. The pressure regulating unit of claim 1 wherein said regulator element is a spring-loaded piston which is slidable in a cylinder guide and is operatively connected to said second sensing diaphragm through a lever means, a fluid flow passage between said outlet chamber and said common outlet being formed between an end of the spring-loaded piston facing said second sensing diaphragm and an annular seat for said piston end. 